1. Field of the Invention
The present invention relates to an image pickup apparatus using a solid state image pickup element such as CCD, and more particularly to signal processing techniques used by an image pickup apparatus.
2. Related Background Art
In a conventional image pickup apparatus such as a video camera which uses CCD and a digital signal processor adapted for field read-out, the following signal processing has been performed to form one frame of a still image constituted of even and odd fields.
FIG. 14 shows the image pickup plane of a CCD in which cyan (C), yellow (Y), magenta (M) and green (G) color filters are disposed at respective pixel positions.
Image data of one frame picked up with this CCD is stored in a memory and combined as shown in FIG. 15 wherein Wb=C+M, Gr=Y+G, Gb=C+G, and Wr=Y+M. After the image data is combined as shown in FIG. 15, an odd field is first formed and then an even field is formed.
With this signal processing described with FIG. 15, however, since the odd and even fields are sequentially processed, adjacent pixels in the vertical direction in each field are disposed with one pixel being interposed therebetween. Therefore, correlation therebetween is low. Since a luminance signal is generated through calculation of pixels with low correlation, the contour emphasis in the vertical direction is shifted to the low frequency area and false chrominance increases.
It is an object of the present invention to provide an image pickup apparatus capable of forming high quality images.
In order to achieve the above object of the invention, there is provided an image pickup apparatus which comprises: image pickup means including an image pickup element with a plurality of color filters disposed in a predetermined layout at respective pixel positions; calculating and processing means for performing calculation and processing by using two sets of adjacent image data in the vertical direction, at each line of image data obtained by the image pickup means; and luminance signal generating means for generating a luminance signal in accordance with an output of the calculating and processing means.
It is another object of the present invention to provide an image pickup apparatus capable of forming high quality images with ease by using a signal processing system of a general video camera.
It is a further object of the present invention to provide an image pickup apparatus capable of selectively using different image signal generating methods by using a simple circuit.
It is still another object of the present invention to provide an image pickup apparatus capable of changing a resolution of images to be picked up, by processing image signals with a common signal processing system.
The other objects and features of the present invention will become apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings.